There are a number of problems with this as the film points out:
1. You have to cut a large hole in the trunk for the spare tire to drop down to road level.
2. There is no way to cover the hole in the trunk for rain, snow and slush (note the CA license tags on the car) so anything in the trunk gets wet.
3. You need a transfer case with a second drive shaft coming out to run this thing as well as the regular rear axle; the pull lever disengages the regular drive shaft.
4. Note the Cadillac clears the house by millimeters rather than inches (again, check the film and watch carefully) as it turns to align the car for the garage.
For those interested, the inventor had it promoted in the do-it-yourself magazines of the day as well as Universal-International's newsreel unit but could not interest investors and found the actual customer demand to be rather limited.
Good idea though...we have something similar today with the radar assist automatic parking system found on a number of upper end imports.